1. Field of the Invention
The present invention relates to an apparatus and a method to provide different pieces of display identification data to a system depending on a connector type.
2. Description of the Related Art
Since a digital visual interface (DVI) was set up as a global standard by the Digital Display Working Group (DDWG), the DVI has been widely adopted in a variety of display devices. However, conventional techniques have failed to transmit extended display identification data (EDID) according to specifications suggested by the Video Electronics Standards Association (VESA), i.e., EDID appropriate for three different DVI input manners, i.e., three different connector types (DVI-I-type, DVI-D-type, and DVI-I-type), due to a unified EDID transmission method in which a connector type is completely ignored.
FIG. 1 is a block diagram of a conventional apparatus to output display identification data. The conventional apparatus includes a DVI connector 11 for a system, a digital visual interface (DVI) connector 12 for an output device, and an electrically erasable programmable read-only memory (EEPROM) 13.
When power is applied to the system, the system supplies power to the EEPROM 13 near the display device via a fourteenth pin of each of the DVI connectors 11 and 12 and reads EDID necessary to identify the display device from the EEPROM 13 via sixth and seventh pins of each of the DVI connectors 11 and 12. By doing so, the system receives data of the display device, such as optimum resolution and color information of a monitor, and sets up an optimum environment for the display device, i.e., the monitor. In the related art, a user has to manually set up such an optimum environment for the monitor. However, a plug-and-play (PNP) function, by which a system may be automatically set up via a display data channel (DDC), has replaced such a manual setting.
In the meantime, while there are three different types of DVI connectors, i.e., a DVI-A-type connector, a DVI-D-type connector, and a DVI-I-type connector, the EDID may only be transmitted via the sixth (DDC clock) and seventh (DDC data) pins of each of the DVI connectors 11 and 12. Therefore, it is impossible to transmit EDID appropriate for different types of DVI connectors. In other words, supposing that the system and the display device are connected via a DVI-D-type connector, digital EDID should be transmitted from the EEPROM 13 to the system. Supposing that the system and the display device are connected via a DVI-A-type connector, analog EDID should be transmitted from the EEPROM 13 to the system. Supposing that the system and the display device are connected via a DVI-I-type connector, any desired one of digital EDID and analog EDID should be transmitted from the EEPROM 13 to the system. However, as described above, in the related art, either digital EDID or analog EDID may be transmitted from the EEPROM 13 to the system because only the sixth and seventh pins of each of the DVI connectors 11 and 12 are set up as DDC signal transmission lines. Therefore, in the related art, irrespective of the type of a DVI connector, in other words, irrespective of the type of display device, either digital EDID or analog EDID may be transmitted. Here, a DVI connector type depends on a display device type.
FIG. 2 is a block diagram of another conventional apparatus to output display identification data. Referring to FIG. 2, the conventional apparatus includes a digital/analog video input/output unit 25, a first memory unit 21, a second memory unit 22, a switching unit 23, and a micom 24.
The digital/analog video input/output unit 25 receives a digital or analog image signal from a personal computer (PC) 26 and outputs display data corresponding to the received signal to the PC 26. The first and second memory units 21 and 22 store analog display data and digital display data, respectively. The switching unit 23 connects either the first or the second memory unit 21 or 22 to the digital/analog video input/output unit 25. The micom 24 determines the image format of the PC 26 according to a selection signal input by a user or a synchronization signal output from the PC 26 and controls the switching unit 23 so that display data corresponding to the image format of the PC 26 may be output to the PC 26. In short, the conventional apparatus to output display identification data of FIG. 2 identifies the image format (analog/digital) of the PC 26 based on the selection signal or the synchronization signal and makes the display data corresponding to the identified image format to the PC 26.
Even though the conventional apparatus to output the display identification data of FIG. 2 has some remarkable improvements, as compared to the conventional apparatus to output the display identification data of FIG. 1, it still has some serious problems, too. In other words, in the related art, only a DVI-I-type connector is taken into account, while the fact that DVI-A-type connectors DVI-D-type connectors are being manufactured and are being widely used is completely ignored. Therefore, the conventional apparatuses to output the display identification data have failed to provide display identification data appropriate for a system and a display device implemented with a DVI-A-type connector or a DVI-D-type connector.